1. Field of Invention
The present invention relates to an antenna, and more particularly to a method for automatically adjusting an antenna and the system thereof, in which the antenna is adjusted according to the wireless signal strength of the received digital signals.
2. Related Art
As the wireless communication technology for transmitting signals can achieve the effect of communicating with remote devices without being connected through cables, it has the advantage of portability, thereby the species of the products adopting the wireless communication technology, such as a mobile phone, notebook, smart appliances with the wireless communication function, are increased gradually. The aforementioned devices transmit signals by wireless waves; therefore, the antenna for receiving wireless waves is an essential device for equipments with wireless communication.
For example, referring to FIG. 1, it is a schematic view of a computer 10 installed with a wireless network card 20 to connect to the wireless local area network (WLAN). The wireless network card 20 contains an antenna 5 mounted on the wireless network card 20. The wireless network card 20 is connected to the computer 10 through the PCMCIA slot, USB port and so on, wherein the antenna 5 is mounted on the wireless network card 20 in perpendicular to the surface of the wireless network card 20. In addition, the wireless network card 20 contains a transceiver 23, a signal sensor 24, and a controller 22. The transceiver 23 is electrically connected to the antenna 5 to transmit or receive wireless signals via the antenna 5. Then, the signal sensor 24 detects the signal strength of the wireless signals received by the antenna 5 to output a feedback signal to the controller 22, thereby the controller 22 changes the value of control current according to the signal strength detected by the signal sensor 24.
In short, when the signal detected by the signal sensor 24 is weak, the controller 22 increases the strength of the wireless signal by increasing the control current. The computer 10 can be quickly connected to the WLAN by the wireless network card 20. However, as the antenna 5 is fixed and unable to be adjusted on the wireless network card 20, the strength of the wireless signals transmitted and received by the wireless network card 20 can not be improved.
Moreover, in recent years, to prevent the strength of the signals from being weaken by the surrounding environment, various relative technologies and devices of adjusting the antenna angle are proposed to be used in other devices in need of receiving wireless wave signals, such as wireless TV, wireless communication devices, so as to maintain the strength of the wireless wave signals received. Furthermore, in the present method of obtaining the relative reference information of the signal strength, the received wireless wave signals directly go through the signal processing (for example, signal amplification, conversion and so on), so as to obtain the strength of the presently received signals as the reference for manual/automatic antenna adjustment.
In the conventional technology, one method relates to search wireless wave signals in multi-orientation in advance and then record various orientations of the searched wireless wave signals for being switched directly later if need be. In other words, the user can switch directly later, and the antenna can adjust the receivable angle according to the pre-recorded orientation, as shown in Taiwan Patent No. 507944. However, during moving, the orientation of the received wireless wave signals is bound to change continuously, so that the method can only be used for the fixed antennas, for example, the receiving antennas of wireless TV.
Furthermore, another method relates to employ an indicator to display the strength of the received wireless wave signals. When the indicator is used with an adjustable antenna, the user can manually adjust the receivable angle of the antenna to the preferable orientation referring to the signal strength displayed on the indicator, as shown in Taiwan Patents No. M245683 and No. 200423588.
In view of the above, the antenna angle plays an important role in the quality of the received wireless wave signals. However, the above-mentioned antenna is adjusted manually, and has the disadvantages that the process of adjusting signal is complicated and the precision of the antenna adjustment is low. Therefore, a method for automatically adjusting the direction of the antenna according to the strength of the received wireless wave signals is provided to overcome the defects of the conventional technology.